[Numpy-discussion] Iterative Matrix Multiplication

Charles R Harris charlesr.harris@gmail....
Sun Feb 28 20:54:40 CST 2010

On Sun, Feb 28, 2010 at 7:35 PM, Ian Mallett <geometrian@gmail.com> wrote:

> On Sun, Feb 28, 2010 at 6:31 PM, Charles R Harris <
> charlesr.harris@gmail.com> wrote:
>> As I understand it, you want *different* matrices applied to each vector?
> Nope--I need the same matrix applied to each vector.
> Because 3D translation matrices must, if I understand correctly be 4x4, the
> vectors must first be changed to length 4 (adding a 1 for the last term).
> Then, the matrices would be applied.  Then, the resulting n*4 array would be
> converted back into a n*3 array (simply by dropping the last term).
Why not just add a vector to get translation? There is no need to go the
homogeneous form. Or you can just leave the vectors at length 4 and use a
slice to access the first three components. That way you can leave the ones
in place.

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